This invention relates in general to a lubricating system and, in particular, to a lubricating system for lubricating a track link hinge joint at the contact surface between a track pin and a track link bushing.
More specifically this invention relates to a track link hinge joint lubricating system wherein the supply of lubricant is contained within a sealed track pin and can be quickly and easily replenished in the field without necessitating replacing any parts of the lubricating system.
Track-type vehicles are frequently used under conditions wherein the terrain is such that a track is required to enable vehicle operation. These vehicles utilize a plurality of track links connected into two parallel endless chains at a track link hinge joint. Track pins span the space between the parallel sides of the links joining complementary ends of adjacent links. One end of each track link is formed with a track link bushing through which the track pin passes to join adjacent links for permitting relative pivotal movement therebetween.
In typical track-type vehicle operational environment, for example sand, dust or mud, much abrasive material is present which creates severe wear problems on the track components. This operational atmosphere causes the track link hinge joint to wear due to entry of abrasive material into the joint which increases surface abrasion of the relatively movable parts shortening operating life. Great stresses are exerted upon the track chains and, therefore, the track link hinge joints by the extremely heavy load supported by the track chain and the nature of the terrain over which the track-type vehicles commonly operate. Under these conditions the track joints are extremely susceptible to the abrasive material wear.
Various attempts have been made to increase the life of the track link hinge joint by such means as improved metallurgy and hermetic sealing and lubricating the joints. However, production costs of such systems have been such that these solutions are not commercially satisfactory. Seals have been developed which protect, with varying degrees of effectiveness, against the entry of abrasives into the track link hinge joint and retain lubricant within the joint to minimize abrasion between the track pin and the track link bushing. Bores in the track pin have been used for retaining and storing lubricant, but precision machining costs and in-the-field machine downtime, which has been heretofore required for replenishing the lubricant within the track pin, have rendered such systems unsatisfactory. Threaded and pressed-in steel plugs have been used but the material cost, and time and trouble in removing worn and corroded plugs when servicing the track links in the field, are both prohibitive and impractical. Other types of plug systems have also been utilized, but require the replacement of a component of the seal assembly when replenishing the lubricant. Such systems are undesirable since they require maintaining a supply of replacement parts for field servicing.
Other problems are created when using a bore formed in the track pin to retain lubricant. Air trapped within the track pin cavity is compressed by the addition of lubricant so that the internal pressure within the cavity increases expelling lubricant from the track pin cavity upon the removal of the lubricant nozzle. Since the lubricant cavity is not vented to atmosphere when lubricant is added, many times an inadequate supply of lubricant results.